CTERM

Returns the number of compounding periods required for an investment at a present value to reach a future value earning a fixed interest rate.

Syntax:

CTERM( interest:Number, future_value:Number, present_value:Number )

where:

interest is the interest rate per period, expressed as a decimal fraction;
future_value is the desired future value of the investment;
present_value is the present value of the investment.

Formula:

CTERM = LN( future_value ÷ present_value )  ∕  LN( 1 + interest )

Example:

How long would it take for £1000 to grow into £2000 at an interest rate of 10% per annum?

The formula

CTERM(0.10, 2000, 1000)

returns the number of periods, 7.27 (years).